For various reasons I have spent the last year looking into the proposed new helicopter performance class system in Australia. This will first be published widely as part of the CASR Part 133/138 NPRM likely to be issued in the first half of 2014. This system will be based very much upon ICAO and European regulations.

Given that this method of regulating performance is new to Australia, I thought it would be beneficial to start an education process in advance of the NPRM. This way, once the NPRM is issued operators need not spend a lot of time trying to figure it all out whilst under the inevitable time pressures that exist for a response. My aim is to try and translate out of the legal jargon, into pilot-speak, and to answer questions as they arise. The focus will be on what the different performances classes actually mean, but (apart from some generalised comment) not so much on which sectors of the industry will have to follow which particular class. The reason I will not get into the detail of whom must follow what, is because CASA have not yet finalised that aspect.

As for my qualification to comment - 28 years flying helicopters; 22 years flying twins; 17 years in EMS; Various operators around the world; Ex-RAN QHI; Nil Offshore; An interest in helicopter performance and knowing our theoretical boundaries!! Some may also know of Jim Lyons, ICAO and European guru on performance matters, whom has been an invaluable source of information, as has Dale South from CASA.

This will be the first in a series of posts, starting with some general background and definitions. I will be very happy to receive comment, particularly from those of you with some exposure to the European system, and therefore having worked under these performance categories. However, bear in mind there will be some significant differences in how they are applied to particular operations in Australia.

During the 1990s ICAO recognised the need to bring regulation of helicopter performance more into line with our fixed wing counterparts. Over several years this process took place, and Europe adopted these policies as regulation well over 10 years ago. The aim was to ensure that flights carrying members of the public and/or operating over populous areas had levels of engine-failure safety comparable to aeroplanes.

In Australia, you may have noticed the various CAOs describing aeroplane performance, and no doubt noticed the absence of a helicopter equivalent. A very simple CASA “Regulatory Policy Notice on Multi-Engine Helicopters’ Operational Performance Standards” has been the only guidance as to how we should operate our multi-engine helicopters. That document will now be superseded by the changes.

Operating within one of the three helicopter performance classes will be a regulatory requirement for most operations. It is expected to be required for most commercial activities, but some Aerial Work operations and Private operations may be permitted to operate outside the performance classes. The detail for these aspects will have to wait for the NPRM.

There will be three Performance Classes – Called PC1, PC2 and PC3. Each class will provide requirements for One Engine Inoperative (OEI) or All Engines Operative (AEO) performance, plus requirements for avoidance of obstacles. For those familiar with Category A Flight Manual procedures, CAT A is not the same as a performance class, but is just one element of a performance class. CAT A, within a flight manual, describes a helicopter certification requirement for multi-engine helicopters, and so tells us what the aircraft can do. It does not tell us when we must apply it, or define the terrain/obstacle avoidance requirements.

Here are some paraphrased definitions:

Category A - With respect to rotorcraft, means a multi-engine rotorcraft designed with engine and system isolation features specified in FAR Parts 27 to 29, and capable of operations using take-off and landing data scheduled under an engine failure concept which assures adequate designated surface area and adequate performance capability for continued safe flight or safe rejected take-off.

This makes CAT A only something that multi-engine helicopters are certified with. The information in the CAT A Supplements tells us how to fly a certain procedure, and defines what size landing areas are required. There can be many different types of CAT A procedures described in the Flight Manual – Clear Area (eg, Runway); Shortfield; Elevated Helipad; Ground Level Helipad; Confined Area; Helideck etc.

Category B - With respect to rotorcraft, means a single engine or multi-engine rotorcraft, which does not meet the Category A requirements.

Category B rotorcraft have no guaranteed capability to continue safe flight in the event of an engine failure, and a forced landing is assumed.An aircraft that is CAT B will therefore be either a single-engine helicopter, or a twin that is not using CAT A for reasons of: lack of manufacturers certification, choice of the pilot/operator, or due to being outside of the CAT A limitations. There is no specific operating procedures or performance data associated with CAT B, unlike for CAT A. CAT B limitations and performance are therefore driven by the standard Rotorcraft Flight Manual (RFM).

Performance Class 1 (PC1) - means the class of rotorcraft operations where, in the event of failure of a power unit, performance is available to enable the rotorcraft to land within the rejected take-off distance available or safely continue the flight to an appropriate landing area, depending on when the failure occurs.

Performance Class 2 (PC2) - means the class of rotorcraft operations where, in the event of failure of a power unit, performance is available to enable the rotorcraft to safely continue the flight, except when the failure occurs early during the take-off manoeuvre or late in the landing manoeuvre, in which case a safe forced landing may be required.

Performance Class 3 (PC3) – means the class of operations where, in the event of a failure of a power unit at any time during the flight, a safe forced landing may be required. (Could be multi or single-engine helicopters)

Safe Forced Landing - Unavoidable landing or ditching with a reasonable expectancy of no injuries to persons in the aircraft or on the surface.

The next post will look at cases of operations outside of any performance category.

Indeed. Thanks for going to the trouble. Will be interesting to see where this goes and if there is an attempt to mandate PC1 in any commercial ops, which will cause issues if it's anything more than runway to runway.

It is so great to have you now helping us all to get a grip on the changes heading our way; and explanations of the new buzz words, and their inbuilt standards, that will effect our future operations.

Over the past decade I have attended many of your public presentations on various regulatory issues and have always come away telling myself I must not miss any future ones, as you are very careful in your research and thoughtful about the way you make it into "plain English". You have won respect from both the operators and the regulator.

Thanks for the supportive comments. Once I get these posts completed feel free to ask any questions for clarification, or ask along the way.

The performance categories are designed to provide a level of safety assurance, following an engine failure, for persons in the aircraft and on the ground. This is done via a procedure of a landing/fly-away without injury (CAT A) or via a Safe Forced Landing (from outside H-V curve). In Private operations (under CASR Part 91) CASA will likely permit operations outside of the performance categories, and so accept a higher risk of injury to persons on the aircraft. The discussion in this post mainly applies to single-engine helicopters, but it may also be applicable to any twins with very poor OEI performance.

If CASA do allow operations outside of the performance classes (eg; probably just Private Ops), there will be differences for operations within populous areas and outside of populous areas. Outside of populous areas a helicopter will be permitted to take-off/land over any kind of terrain/bush/water (within RFM limits), in the full knowledge that an engine failure may lead to injury/death for the occupants.

For take-off and landings within populous areas the pilot must preferably have a Safe Forced Landing area (smooth flat surface), or failing that, an “Emergency Landing Area” identified. The Emergency Landing Area is not completely defined, but in essence is an area the helicopter can realistically reach without endangering persons or property on the ground or water. It could be a golf course, park, river or any kind of open space. Forced landing options such as houses or public roads will not be acceptable under this regime.

Once above the minimum safe height for flight, generally being 500ft (1000ft over populous areas) all helicopter operations are expected to be able to land following an engine failure without endangering persons or property on the ground or water. So once again this means retaining options to avoid landing on houses, buildings or busy roads etc.

So to summarise operations outside of the performance classes: Firstly only limited types of operations will be allowed. Secondly, for this lowest level of engine failure accountability, the persons on the aircraft may be at risk, but not members of the public, or property on the ground.

Thanks for the briefing, very kind of you to share your knowledge with us.

I defer to your expertise, and ask you to clarify the following if possible.

"For take-off and landings within populous areas the pilot must preferably have a Safe Forced Landing area (smooth flat surface), or failing that, an “Emergency Landing Area” identified." (Underlined comment).

Without being pedantic, is it "must" or "preferably" ?

I have been concerned about the new rules for sometime (which I read in draft), and amongst others are very worried about the effect this will have on singles operating in populated areas - I am privy to a number of submissions to CASA about the matter as well - all sharing the same concerns (which seem to be ignored by CASA). My (fully approved) helipad is in a commercial zone (in a big city), and it would be very hard for me to operate a single if the rules are as tough as predicted and / or indicated by yourself. I have around 500 mtrs of horizontal flying over roads, buildings, vacant blocks (at least for now) to reach bushland / rivers and 500 + feet. It was always my plan to land on a road or a vacant block if I ever had a problem. I suspect vacant blocks are OK...but these will no doubt be built on in the future. I have been flying in / out of the pad for many years, without a) problems or b) complaints from anyone.

If there is no defined meaning for "Emergency Landing Area"...perhaps that is my out. There are plenty of large grassed areas in the front of buildings...I wonder if that will be OK ?

I have also read CASA quotes stating along the lines of "do not worry, these new rules will not prevent singles from flying over populous areas"...that does not seem to be 100% correct.

Either that or I need to save up a few million and buy an old twin !

I would be interested in your comments, as would the many other people on BS that operate their own machines for private ops out of big cities.

Well if we let this happen we will be in a bit of trouble wont we?So a fully load truck has a steer tire blow going down a hill in a busy suburb and drives through your house but that is OK?That has happened more times in the whole helicopter history in Australia than any helicopters crashing through roofs, yet we get the rule making it harder/impossible for us to operate.

HiIt's look like we follow the European trend , all single engine helicopter operation will be band over city , we already had contract canceled from small operator (single turbine engine) to bigger organization with twin helicopter services

It's not all doom and gloom. Singles will not be banned over a built up area, just not below 1000' agl. The app and depart routes may change and some inner city pads may change their spec's, but it doesn't mean down tools.

For example the R44 doing traffic spotting in most capital cities normally operates at 1500', they can still do that.I have seen an R44 doing power line patrols in and around the edge of towns, well they can't do that in the future.

There may be some effect on schools and where they send their students to train, PFLs, confined areas, etc, but I assume they will still have issues that will not be impossible to overcome. Just be creative.

What you leave behind is not what is engraved in stone monuments, but what is woven into the lives of others.

Depending on who you talk to, the situation may well be much worse than what you say. It depends a lot on the interpretation of the new rules. A very smart long time driver worked out that to fly from Camden to Warnervale in a heli, and be 100% within the rules (true reach to emergency landing areas) you would need to fly IFR at 5,500 feet minimum. Yep, that's going to be a lot of fun !? Sydney readers note the lack of people on that flight route too.

I would suggest we should be asking the question "why ?". There is no basis in fact for the introduction of rules that will effectively prevent singles flying over populous areas. Of course, by simply reducing the amount of helis flying around, CASA will be able to show (mathematically) a drop in accidents...and that may well be what they want to achieve.

A much more knowledgeable airman than me has a view that the new rules will be the death of singles flying anywhere near a city.

This looks very much to me like rules for rules sake...with no real benefit to anyone.

Can someone please tell me when was the last time there was a heli crash in Australia due to engine failure - over PEOPLE ? I can't remember one, but no doubt there has been one...or why would we be accepting these new rules ?

The AHIA should be going into bat for us all...and for the sake of commonsense.

CASA will come to you with the "intention" of the new rules, but it has NOTHING to do with what they intend the rules to say. What it will come down to is how the CASA, or council, or NIMBY lawyers interpret the rules as they are written while they are prosecuting you for flying too close to their precious place.

We have just been through the same thing in NZ, rules changed to fall into line with ICAO, this isnt intended to shut down single ops in cities etc, well all the rescue helicopters that are based in town have had to go twin, as CAA come around with a big stick and say how can you safely get out of here with a single? Quite safely if the engine doesnt quit, and the last time an engine quit was when???

unfortunately that answer is not acceptable.

this will limit what singles can do in and around cities, as they only need to say that you could cause harm to a third party in the event of an engine failure.

Along with the 3 performance class , there are now 'Hostile Environment' and 'Non Hostile Environment'

Hostile environment’ means:(a) an environment in which:i. a safe forced landing cannot be accomplished because the surface is inadequate;ii. the helicopter occupants cannot be adequately protected from the elements;iii. search and rescue response/capability is not provided consistent with anticipated exposure; oriv. there is an unacceptable risk of endangering persons or property on the ground.

‘Non-hostile environment’ means an environment in which:(a) a safe forced landing can be accomplished;(b) the helicopter occupants can be protected from the elements; and(c) search and rescue response/capability is provided consistent with the anticipated exposure.In any case, those parts of a congested area with adequate safe forced landing areas shall be considered non-hostile.

So imagine a jet ranger or any other single engine helicopter flying over vast amounts of water , over mountainous areas or areas covered in forests..............and being performance class 3....not going to happen

There will be helicopter lanes that will allow single to travel around the coast and that will be your lot....

 ‘Operation in performance class 1’ means an operation that, in the event of failure of the critical engine, the helicopter is able to land within the rejected take-off distance available or safely continue the flight to an appropriate landing area, depending on when the failure occurs. ‘Operation in performance class 2’ means an operation that, in the event of failure of the critical engine, performance is available to enable the helicopter to safely continue the flight, except when the failure occurs early during the take-off manoeuvre or late in the landing manoeuvre, in which cases a forced landing may be required. ‘Operation in performance class 3’ means an operation that, in the event of an engine failure at any time during the flight, a forced landing may be required in a multi-engined helicopter and will be required in a single-engined helicopter.

Not looking good for single and poor twin helicopters.....hense europe has been busy replacing poor twins with Perf class 1 , were have these helicopters gone to Australia............BOLKO 105 anyone

Can someone please tell me when was the last time there was a heli crash in Australia due to engine failure - over PEOPLE ? I can't remember one, but no doubt there has been one...or why would we be accepting these new rules ?

From the list I have collated, of 157 aerial filming accidents, both fixed wing and rotary, worldwide, since year 2000, none have resulted in serious injury to those on the ground and there is just one report of a minor injury.

136 involved rotary.

Of the 136 total, 6 were caused by engine failure, all in single engine craft ( 2 x exhaust valves, 1 x turbine blade, 1 x loose pressure hose, 1 x oil leak, 1 x bearing)17 incidences by other mechanical faults19 of the rotary accidents were in twins, none of these have been proven to be caused by engine failure.

Of the 136 total, 23 incidents were on or near buildings.1 on top of NY city building4 into city streets with minor damage2 into village houses1 in narrow village streetThe rest were in industrial areas, urban open spaces or city or urban parks.Engine failure did not feature in any of the accidents where buildings were damaged.

Whilst the cause is "unknown" in some of the 136 incidents, engine failure is unlikely in the majority of these unknowns (such as AS355 Lake Eyre crash)

So, between 2000 and 2013, during aerial filming, no twins have crashed or made emergency landings due to an engine failure and no buildings had been damaged by crashes attributed to engine failures in singles or twins.There have been no deaths or serious injuries to the public in any of the 136 incidents.

Can this data be extrapolated to helicopter ops in general? Does aerial filming involve as much flying over or near built-up areas as other types of helicopter work?

I think MJB's reasoning is sound, pure and simple (and very well proven) risk assessment. The governing bodies must produce a risk based reason for any legislation, and in the case of rotary aviation and the risk to humans the likelihood MUST be taken into account otherwise the processes put in place will NOT reflect the real situation, the Action taken following a risk assessment should be Appropriate to the Likelihood. In almost all spheres of life authorities must make decisions regarding public safety and they should always justify their reasoning.

Firstly, there is no doubt that CASA will be making moves to ensure the general public on the ground are protected from the risk of engine failure. My understanding is that private operations will remain acceptable over populous areas, provided you have engine failure options that allow you to avoid hurting people via an emergency landing area. Preferably you will have a safe forced landing area (they are encouraging a higher standard), but you can get away with an emergency landing area. Obviously CASA will need to define this further. I also want to avoid too much speculation on specific cases, because it will be up to CASA to interpret - I am just trying to translate some knowledge for the wider audience to ensure people can get the gist of what is coming.

We are probably all aware that the intent has always been that if we are flying over populous areas above 1000ft we are expected to do our utmost to avoid hurting people on the ground. I do not believe this will change. Next time you fly around the cities check out all the open spaces there are - lots.

For others:

I would ask people to take the European examples with a grain of salt. There is no doubt that if we completely adopted the European regs overnight it would kill a lot of our industry. CASA are using ICAO/European terminology to bring many things into line internationally, but it does not mean they will apply the performance categories in the same way. My PC1 topic is coming up, but I have received no inkling that commercial operators will have to be PC1, as is the case in Europe. I have seen no mention anywhere of applying the hostile/non-hostile rule in Australia.

As for the merits of engine failure regulation, given the relative absence of deaths from engine failures. I feel that CASA is looking like taking a much stronger risk management approach to this issue than what Europe did, which is a good thing. It might pay to look at these changes as being more about alignment of terminology and principles, rather than alignment of regulations. In the meantime, if anyone has some bright ideas for CASA on how they should regulate for preventing the deaths that are happening, I am sure they will be keen to here some well thought out arguments??

Cheers,RN

Last edited by R Nest on Mon Nov 11 2013, 07:09, edited 1 time in total.

The next level up in engine failure safety (above not being in any performance class) is PC3. PC3 means the class of operations where, in the event of a failure of a power unit at any time during the flight, a safe forced landing may be required. This could apply to either singles or low-powered twins.

The normal principle of PC3 is that if you have an engine failure during the take-off or approach, you are able to conduct a safe forced landing. During the take-off this will only be possible if you are outside the boundaries of the H-V curve, or utilising a CAT A procedure (for twins). Once in cruise flight, the requirement for a safe or emergency forced landing area is removed, unless over populous areas – more on that later. Note that this is a step down from PC3 in Europe where a safe forced landing is expected at all times of flight, even in the cruise.

As mentioned in my first post, I will not venture too much into which types of operations must abide by the PC3 requirements. Very broadly speaking you could consider PC3 as the likely standard for Day VFR Aerial Work (Part 138), or Day VFR Charter (Air Transport Part 133) operations for light helicopters (<10 pax seats).

If you are required to operate PC3, you may be able to do so with some exemptions from the requirement for a safe forced landing. Any exemption will be driven by the exact type of operation you are conducting, and/or whether or not it is over a populous area.

Over non-populous areas it will probably be permissible to operate PC3 without a safe forced landing area, with the acceptance of injury to persons on board the aircraft. But again this may be dependent on your type of operation. Over populous areas it may also be permissible to conduct PC3 take-offs, landings, and enroute flight without a safe forced landing area, but such operations will be conditional upon the risk management requirements discussed below.

Some types of Aerial Work or Air Transport (Charter) operations may gain permission to operate PC3 over populous areas without having safe forced landing areas available. These operations have higher levels of Safety and Risk Management Systems than is expected for Private operations so are starting from a stronger safety base. Such operations without the safe forced landing area will be conditional upon meeting a number of operational and engine requirements, all of which are designed to either minimise the chance of a surprise engine failure and/or minimise the consequences should the engine failure occur. Here are some examples of the types of things that may be required.

1. The rotorcraft must be flown in a way that minimises the time during the flight over the area in which a suitable forced landing area is not available;2. The rotorcraft must be equipped with a magnetic particle detection system that monitors the engine and the main and tail rotor transmission gearboxes, and includes a flight deck caution indication for each gearbox.3. The Operations Manual must include: risk assessment and management procedures for flights over populous areas; training for pilots in recognising and reacting to in-flight emergencies in accordance with the rotorcraft’s flight manual; and, training for pilots in conducting autorotative descents to locations with limited access to suitable forced landing areas.

There has also been some discussion about requiring engine Usage Monitoring Systems, back-up fuel control systems, and even turbine engines. However, before you get too excited by these costly prospects, some of these higher-end requirements are only likely to be placed on the higher risk operations over populous areas. Examples might include flights below the normal 1000ft minimum altitude, or specialised emergency service operations over cities and towns. So there will be a PC3 baseline of a safe forced landing, with possible variations around specific types of operations – we will have to wait longer for CASA to define this.

So far PC3 is probably sounding the same as having no performance category, as discussed in my second post. However, there are some further requirements regarding PC3 to be aware of:1. PC3 take-off or landings specify the need to not exceed the Hover IGE weight limits, or Hover OGE weight limits if the IGE hover is not possible due to surface or terrain. This is not about what the helicopter can physically do (with your expert skill), but about what the charts say it can do.2. The take-off weight must allow you to avoid all obstacles on take-off, by a margin defined in your operations manual (eg 10ft) with all engines operating. So if you hit something you were obviously not PC3!!3. You must have enough power to reach the minimum safe height with all engines operating, and enough power to conduct whatever type of operations you wish to conduct at altitude (eg HOGE for filming perhaps).4. A baulked landing (overshoot from an approach) must be possible at any time with all engines operating, and must also allow you to miss the obstacles by the defined margin.5. The operations manual must describe how you are to determine all of the above.

So PC3 will be the likely regime for Day VFR Air Transport (Charter) with <10 passenger seats, plus for many Day VFR Aerial Work functions. The exemptions from having a Safe Forced Landing area will only be applied to certain sub-categories within these operations, and be conditional upon meeting a number of risk reduction strategies.

The next post will move to the highest level of engine failure accountability, being PC1.

RN

Last edited by R Nest on Sun Nov 17 2013, 07:39, edited 1 time in total.

Performance Class 1 (PC1) - means the class of rotorcraft operations where, in the event of failure of a power unit, performance is available to enable the rotorcraft to land within the rejected take-off distance available or safely continue the flight to an appropriate landing area, depending on when the failure occurs.

PC1 is an operational regime that is meant to provide absolute assurance that an engine failure at any time of the flight will not result in any damage to the aircraft (or exceeding of limits), or injury to persons in the air or on the ground. It is designed to protect both passengers and the public, and is similar to what is expected of fixed wing airline operations. It is only possible in multi-engine helicopters, and only in those types certified with CAT A capabilities.

PC1 is not just CAT A. CAT A is a certification standard that is driven by weight and/or passenger seats, but generally most helicopters over 3175kg (7500lb) will be certified for CAT A, as will some models under that weight. Part of the CAT A certification is to provide data to the pilots that allows them to calculate things like take-off distances, reject distances, OEI climb gradients etc. To operate PC1 we must also know when the CAT A procedures are to be applied, what obstacles to consider, and by how much we must clear those obstacles. So PC1 is a description of a regulated operational requirement which, in order to meet it, requires CAT A certification and procedures.

Helicopter Landing Site (HLS) standards and design are also vital for allowing PC1 operations. At the moment CASA are still working on what this might look like, but the following list gives you a basic sample of what is required to make an HLS PC1 capable:1. The dimensions of the Final Approach and Take-Off Area (FATO) must allow AEO, and OEI reject operations, without the risk of striking surrounding obstacles during approach, touch-down, lift-off, departure, or taxi manoeuvres. The reject area could be a helipad or a runway-type environment.2. The load-bearing capability of the helipad must allow AEO and OEI operations without the risk of collapsing under the expected loads.3. The markings/lighting of an HLS must allow the relevant CAT A procedures to be flown within the required accuracy, and to give pilots guidance on exactly where they should land.4. The HLS surface must be adequately constructed and of limited slope.5. Surrounding obstacles must be surveyed if they lie within specified departure splays (explained later).6. Obstacle-free gradients within the departure splays must be defined.7. Accurate wind, temperature and pressure data must be available so as to allow pilot calculations of helicopter performance.

So to operate PC1:1. First we need to know that the HLS is constructed to allow PC1 for our helicopter (just like big aeroplanes on runways);2. Then we need to know what the obstacle environment looks like, based on a formal survey of the required departure splays (just like airports);3. Then we need to know by how much height we must clear the obstacles by;4. Then we need to see if our helicopter has a CAT A procedure that allows us to use that sized HLS, and clears the obstacles by the requisite amounts.

Lets look at each of these four aspects in more detail, starting with HLS construction. In designing and constructing a HLS, the operator will need to define the largest/heaviest aircraft permitted to use it. Without going into the full detail, the expectation for an onshore site is that the HLS will need a minimum width and length equal to twice the D-value (D=maximum dimension of the helicopter), or as specified in the Flight Manual. In particular there will need to be sufficient space for a rejected take-off either back onto the helipad, or onto the runway.

Departure splays – there are several variations on what these will look like depending upon the aircraft size and whether in VMC, NVMC or IMC. For example, the NVMC expectation is that the departure splay will start out from the end of the HLS, with a total width of 2D then diverge at 15% out to a maximum width of 10 x rotor diameter (10R). We will need to consider any objects within this splay up until we can achieve 1000ft. If our CAT A take-off procedure requires a back-up or lateral manoeuvre, we also need to consider obstacles in that direction using a similar splay. I failed to get a diagram up!!

Obstacle clearance – To meet these requirements we will need to clear any obstacles within the above splay by at least 35ft, following an engine failure. At or prior to our CAT A Take-off Decision Point (TDP) we are expected to reject back onto our HLS. At or after our TDP we are expected to fly away avoiding all obstacles by at least 35ft (although 15ft is acceptable if we are still over a runway-type environment). We must clear all such obstacles within the splay up until we achieve 1000ft above the HLS.

Helicopter CAT A Capability – When considering PC1 operations from a HLS, the pilot can have an option of several different types of CAT A procedures that may be published in the Flight Manual. CAT A procedures may be published as Clear Area (Runway), Shortfield, Confined Area, Ground Level Helipad, Elevated Helipad, Helideck etc. The pilot should choose the type of CAT A procedure that will work for the type of helipad being used, and for the obstacles present within the splay. Many of the vertical-type CAT A procedures permit upwards extensions of the TDP, which will improve the chances of achieving the required obstacle clearance.

In addition to clearing the obstacles by 35ft, there are some other minimum requirements on meeting PC1:1. Must be within the weight limits for the CAT A procedure selected.2. Must fly the CAT A procedure as published.3. For shortfield or runway type environments, the rejected take-off distance available (RTODA) must exceed the rejected take-off distance required (RTODR).4. If OEI below 200ft you must achieve a minimum of 100fpm rate of climb for the departure and approach. 5. If OEI above 200ft you must achieve a minimum of 150fpm rate of climb at 1000ft for the departure and approach. (Note: You may need much more than this to clear the obstacles. For example, ICAO recommends PC1 helipads are designed with a maximum of a 4.5% obstacle-free gradient. At a speed of 70kts this would require about 320fpm rate of climb!)6. If OEI during the cruise you must be able to maintain at least 50fpm rate of climb at a safe height. (This is slightly less than the old 1% rate of climb commonly used for IFR Charter in Australia.)7. Any OEI landings must clear obstacles on final approach by an adequate margin (eg, 15ft), and the landing distance available must be greater than the landing distance required.8. An OEI balked approach must clear all obstacles by 35ft.

So after all this technical stuff how can we summarise PC1. Licensed aerodromes will often have the data to allow pilots to operate PC1. They all provide departure splays, take-off distances, reject distances, and obstacle-free gradients. Although there are some aspects regarding the diverging splay angles and distances (page 42 of ERSA) that differ from the usual helicopter requirements, a comparison reveals that the helicopter splays will often stay inside the aerodrome splays. This makes larger runways (CN3) acceptable for IFR PC1 and some smaller runways (CN2) acceptable for VFR PC1 depending on OEI climb capability.

Onshore helipads – Many ground level helipads will meet size and strength requirements, but few will currently have surveyed splays with obstacle-free gradients published and available to pilots. Until then they should not be considered as being PC1 capable. Surrounding obstacles would need to allow CAT A published profiles to be flown with the requisite obstacle clearance.

It should also be noted that different aircraft types require different surveys for helipad take-offs. For example some types will utilise a back-up manoeuvre (therefore need a rearwards and departure path survey), some will utilise a vertical take-off (departure survey only), and some will utilise a lateral take-off manoeuvre (lateral and departure path survey). So helipad operators should consult closely with helicopter operators to determine the exact needs for the expected life of their helipad. I would recommend surveys to cover all options, or they might find that future aircraft can’t use the helipad. This issue will be most important for future hospital helipad design, or urban Charter (Air Transport) heliports. I note the proposed new Brisbane River helipad, and hope they are designing this with PC1 in mind!!

Onshore Elevated Helipads – Many aircraft types have elevated helipad CAT A procedures published. These generally rely on using clear space below the elevated helipad to “drop-down” and convert height into a speed that allows a safe OEI climb. Because of the lack of control and complexities surrounding onshore elevated helipads (particularly hospitals in Australia) I would advise that “drop-down” techniques not be planned outside of the offshore environment. It will be very difficult to map an adequate survey for drop-down techniques, and the risk management of such procedures would be quite a challenge for achieving PC1.

This does raise the question of the legitimacy of using ground level helipad CAT A procedures from sites that are ostensibly “elevated”, such as hospital helipads. This would need to be discussed thoroughly with CASA, but I feel it should be possible to make an adequate safety case on the basis of the elevated site having adequate surrounding visual references to assist with accurate flying of the procedure.

Offshore helidecks – These are often well prepared in terms of dimensions, markings and strength. With a usually flat ocean surface surrounding they are also easily assumed to have a straightforward obstacle-free gradient (depending upon variables of swell, waves, tide and other vessels). Helidecks also require different methods of showing an obstacle-free gradient (CAAP 92-4), in that their survey drops down below the helideck to allow for CAT A drop-down techniques to be used. However, the obstacle environment of an oil/gas platform/vessel often makes it difficult to meet the CAT A cross-wind requirements for approaches/departures. For these reasons PC1 is not normally a mandatory standard in the international offshore sector because it would significantly limit commercial operations. These operations have other mitigation strategies that will be discussed later in the PC2 topic.

New helipad design and survey standards are coming soon (old ones were in CAAP 92-2). These will align future helipad design with the performance category system and so make it simpler for operators to work out how to meet the performance categories. CASA’s current intention seems to be that PC1 standards will not be required unless the helicopter is operating Air Transport with more than 19 passenger seats, which effectively rules out all Australian operations. However, like Europe, it is quite likely that one day PC1 requirements will be extended into more of our commercial operations. This will require a combination of appropriate aircraft (many capable CAT A aircraft are already around) plus helipads built/modified to PC1 standards. I have no idea when this might happen and I don’t believe CASA have a solid timeline either.

In the next post I will start on the performance category that will be most relevant to many twin-engine commercial operations – PC2.